Method StartSnappingFreqSelection

src/tracks/ui/SelectHandle.cpp:1363–1403

}

void SelectHandle::StartSnappingFreqSelection(SpectrumAnalyst &analyst,
   const ViewInfo &viewInfo, const WaveChannel &wc)
{
   static const size_t minLength = 8;

   const double rate = wc.GetRate();

   // Grab samples, just for this track, at these times
   std::vector<float> frequencySnappingData;
   const auto start =
      wc.TimeToLongSamples(viewInfo.selectedRegion.t0());
   const auto end =
      wc.TimeToLongSamples(viewInfo.selectedRegion.t1());
   const auto length =
      std::min(frequencySnappingData.max_size(),
         limitSampleBufferSize(10485760, // as in FreqWindow.cpp
            end - start));
   const auto effectiveLength = std::max(minLength, length);
   frequencySnappingData.resize(effectiveLength, 0.0f);
   wc.GetFloats(
      &frequencySnappingData[0],
      start, length, FillFormat::fillZero,
      // Don't try to cope with exceptions, just read zeroes instead.
      false);

   // Use same settings as are now used for spectrogram display,
   // except, shrink the window as needed so we get some answers

   const auto &settings = SpectrogramSettings::Get(wc);
   auto windowSize = settings.GetFFTLength();

   while(windowSize > effectiveLength)
      windowSize >>= 1;
   const int windowType = settings.windowType;

   analyst.Calculate(
      SpectrumAnalyst::Spectrum, windowType, windowSize, rate,
      &frequencySnappingData[0], length);

   // We can now throw away the sample data but we keep the spectrum.
}

void SelectHandle::MoveSnappingFreqSelection(
   AudacityProject *pProject, ViewInfo &viewInfo, int mouseYCoordinate,